1. Field of the Invention
The present invention relates to image forming apparatuses such as copiers and laser beam printers, in which an electrophotographic process is used.
2. Description of the Related Art
In a known image formation method used in a related-art electrophotographic color image forming apparatus, images of different colors are sequentially transferred onto an intermediate transfer belt and then collectively transferred from the intermediate transfer belt to a recording medium, thereby forming an image on the recording medium. When an image is formed in the method as described above, toner remains on the surface of the intermediate transfer belt after the image formed on the intermediate transfer belt has been transferred onto the recording medium. In order to remove this residual toner, a cleaning blade is provided. The cleaning blade is in contact with the intermediate transfer belt so as to scrape the residual toner off the intermediate transfer belt.
In the case where such a cleaning blade is used to scrape off the residual toner, when frictional forces between the cleaning blade and the intermediate transfer belt are large, noise may be generated by vibration of the cleaning blade or image quality may be degraded due to curling of the cleaning blade. In order to address this, Japanese Patent Laid-Open No. 2007-155750 discloses a technology. With this technology, a toner image is formed in a non-image forming region on an intermediate transfer belt so as to supply toner into a nip between the intermediate transfer belt and a cleaning blade. Thus, frictional forces between the cleaning blade and the intermediate transfer belt are reduced, and accordingly, noise or faulty cleaning is suppressed.
A toner image may be formed constantly at a certain timing in a non-image forming region by, similarly to the related-art, forming a toner image used to reduce frictional forces between the cleaning blade and the intermediate transfer belt at a specified timing after an image is formed in accordance with the conveying direction length of a specified recording medium. However, for example, when a recording medium, the conveying direction length of which is longer than that of the specified recording medium, is conveyed, the toner image formed in the non-image forming region may be unintentionally transferred to the recording medium and contaminate the recording medium as illustrated in FIGS. 6A and 6B.